Animal Hospital
Quality Care
Dedicated staff
Conveniently located

Hours of Operation:

Monday: 8:30 a.m.-7 p.m.
Tuesday: 8:30 a.m.-7 p.m.
Wednesday: 8:30 a.m.-5 p.m.
Thursday: 8:30 a.m.-7 p.m.
Friday: 8:30 a.m.-7 p.m.
Saturday: 8:30 a.m.-2 p.m.
Sunday: Closed

Permethrin/pyrethrin toxicity: whole lotta shakin' goin' on

There are many over-the-counter flea and tick products available nowadays and it is much more convenient to pick it up while we are out purchasing other items from the store. Unfortunately, there are either staff that are not qualified to answer questions about the product, or no one to speak to at all.

One of the most common ingredients in the over-the-counter topical flea and tick preventatives is permethrin. Permethrin is in a class of chemicals called pyrethroids, or synthetic pyrethrins. Pyrethrin is a naturally occurring compound derived from the flower Chrysanthemum cinerariaefolium.

How do permethrin and other pyrethroids work? They are neurotoxins and very effective against a host of external parasites. They affect certain portions of the central nervous system by causing hyperexcitability (tremors) and, eventually, death. Luckily, permethrins and other pyrethroids are toxic to insects and other parasites but do not readily affect most mammals. Unfortunately, cats are one of the few mammals that are very sensitive.

How are cats exposed to this chemical? Luckily, there are very few topical antiparasitics (medications to prevent fleas, ticks and other external parasites) on the market today for cats that contain permethrin or other pyrethroids. However, there are plenty of antiparasitics for dogs that contain permethrins. Most times it is the owner unknowingly applying their dog's medication on the cat (whether to save money or just not realizing) or there is a dog and a cat in the same household that are very friendly and the cat gets the chemical on their fur. Permethrins can be absorbed through the skin, but most times the cat is grooming him or herself and ingests the compound.

The onset of the symptoms occurs anywhere from one to three hours after exposure. One will notice that the cat starts having tremors that don't stop. Depending on the concentration of permethrin in the product, the amount ingested or the sensitivity of the particular cat, the tremors may be either very mild or severe. These tremors are dangerous for a few reasons: it causes a rapid rise in the body temperature, the cat can't eat or drink so he/she becomes rapidly dehydrated, and these tremors release breakdown products of muscle metabolism that are toxic to the body (particularly the kidneys).

Although the first instinct is to remove the remainder of the product from the skin to eliminate further exposure, that may not always be the best option. If the cat is already shaking pretty badly, the added stress and stimulation will only worsen the symptoms. Getting your cat to your veterinarian or to the nearest emergency clinic (if your vet is not open) so that the vet and staff can place an IV, put your cat on fluids and give muscle relaxants before washing may save their lives.

When washing one has to use dish soap rather than shampoo to make sure to get any residue off. After that it usually takes about one to three days for the chemical to clear the system. In some cases your cat will have to spend the entire time at the animal hospital. Other times they can be released (if eating and drinking) on oral medication to reduce the tremors.

The best (and least expensive) way to treat this is to be aware of the ingredients in any products you put on your cat. If you are unsure, check with your veterinarian's office first or purchase products from your veterinarian's office that are approved for cats.

Matthew Kearns, DVM